All known higher life forms require a subtle and complex electrolyte balance between the intracellular and extracellular milieu. In particular, the maintenance of precise osmotic gradients of electrolytes is important for good health. Such gradients affect and regulate the hydration of the body as well as blood pH, and are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control. Serious electrolyte disturbances, such as dehydration and over hydration, may lead to cardiac and neurological complications and, unless they are rapidly resolved, may result in a medical emergency.
For these reasons, instruments exist for the analysis of patient samples for diagnosis purposes. For example, the measurement of electrolytes is a commonly performed diagnostic procedure. Electrolytes measured most often include sodium (Na+), potassium (K+), and chloride (Cl−). One known method for measuring electrolytes is potentiometric measurement of ions using individual sensors employing ionophores to selectively attract the ion of interest. For example, an ion selective electrodes (ISE) measurement of sodium (Na+), potassium (K+), and chloride (Cl−) electrolytes is performed by the V-LYTE® IMT Module of the Dimension Vista® Integrated System manufactured by Siemens Healthcare Diagnostics Inc. of Newark, Del.
A problem with conventional sample electrolyte measurement systems is electrolyte result variability and these conventional systems do not provide a separate or secondary quantitative means for verification of the measured results of an electrolyte measuring module on, for example, a clinical chemistry analyzer. This may lead to errors or inaccurate results since conventional systems and methods do not provide a means to detect errors in individual result calculations that could be caused by, for example, electrical or chemical interferences in the ISE measurements.
Some conventional systems attempt to address this problem by monitoring the output of the individual ISE sensors and setting limits for electrical voltage drift that may occur when interferences are present. Also, simple tests for the presence or absence of sample may be performed to check for gross positioning errors. These techniques, however, do not provide a second or separate quantitative means for verification of the calculated results of a sample electrolyte measurement.
What is needed is a separate quantitative verification process that can detect or flag suspect samples where the measured electrolyte results do not fit the expected electrolyte results as determined by this separate quantitative means.